000
FXUS63 KEAX 100755
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
255 AM CDT Wed Apr 10 2024

.KEY MESSAGES...

- Rain Showers Wednesday - Thursday

- Gusty Winds Thursday - Friday

- Anomalously Warm Temperatures This Weekend

&&

.DISCUSSION...
Issued at 254 AM CDT Wed Apr 10 2024

An H5 ridge axis has pushed through the Northern Plains forcing a
surface anticyclone into our area. The thermal boundary ahead of
this has been pushed into far southern Missouri. Temperatures have
not dropped much with this thermal boundary passage, with clear
skies allowing insolation to recover temperatures yesterday
afternoon. The main feature to keep an eye on for the next 36 hours
is the deep trough axis that is currently positioned across western
Texas, with associated surface cyclone that is centered along the
Gulf coast of Texas. This is still sitting ahead in an area of
favorable dCVA for further deepening, and inverted surface troughing
extend northeastward into the Ozarks Region. This system has caused
the thermal boundary that passed through our area yesterday to stall
in southern Missouri. With the weak ridge axis to our north having
passed, another short-wave trough extending from a deeper closed-low
over Canada will result in an period of mid-level height falls this
afternoon through Thursday morning. The southern trough with the
stronger vort max will be the more dominant force over the next 36
hours, and is expected to push the stalled thermal boundary back
northward toward the Interstate 70 corridor. Increasing convergence
through the late morning and early afternoon is expected to start
light rain shower activity for our southern counties, slowly
spreading northward and northeastward through the remainder of the
afternoon. The heaviest QPF axis continues to be south and southeast
of our forecast area along the Interstate 44 corridor, as this is
where the better kinematics and mid-level support will be located.
For our counties south of Interstate 70, synoptic scale ensemble
members continue to depict 50 to 60 percent probabilities for
measurable precipitation, and about to 40 to 50 percent for a
threshold of 0.10 inches. The probabilities quickly drop off further
to the northwest, with ensemble probabilities between 15 and 20
percent to about the Hwy. 36 corridor for measurable precipitation.
Deterministic GFS and ECMWF has been very dry for the northwestern
third of our CWA. With the boundary being pushed further south and
perhaps struggling to get back further north due to the northern
short-wave, that is possible. However, with this robust of a mid-
level trough coming out of Texas, cannot rule our light shower
activity up to about the Hwy. 36 corridor by this afternoon. Recent
CAM trends have also been very light QPF north of Interstate 70,
with HREF mean values less than 0.10 inches, and right around 0.10
inches for our far southern counties. GEFS and other ensemble means
for our southern counties around 0.20 inches of QPF. Another
limiting factor to rainfall this afternoon will be the storm mode.
The stronger thermodynamic instability will be well south of the
area, thus greatly limiting the potential for convective storm
modes. As for temperatures, our far northwestern counties may be
able to hit the lower 70s this afternoon, as cloud cover may hold
off there until after peak heating. Inner-quartile values amongst
NBM members in our northwest are between 71 and 74. Elsewhere,
temperatures will mainly be in the upper 60s as cloud cover
continues to increase through the afternoon.

By Thursday morning, the southern trough vorticity begins to wrap
around the system and the surface cyclone stalls allowing the system
to become vertically stacked. With the short-wave trough to the
north though, there is enough of a push that the stronger
convergence continues to move eastward. Deterministic solutions
continue to depict strong moisture transport to the backside of the
system which will maintain stratiform cloud cover through Thursday,
and may still squeeze out light rain especially for our eastern
counties. Recent CAM guidance, in particular the HRRR, has depicted
some weak shower activity. However overall probabilities for
exceeding much more than a few hundredths of QPF Thursday morning
through Thursday afternoon remains limited, the heavier QPF for
Thursday is centered just east of the Mississippi River Valley, as
this is also the area with better Q-Vector convergence and more
supportive mid-level kinematics. Gusty northerly winds will be the
bigger story starting Thursday. The pressure gradient will remain
strong on the backside of cyclonic flow, while an amplified ridge
axis over the Intermountain West and secondary axis over the Four
Corners Region helps to build a strong surface anticyclone near the
TX/OK Panhandle Region. While temperatures will not drop
drastically, there will CAA around 925mb that could help to provide
stronger momentum transport with wind gusts between 30 and 35 kts. A
few model soundings have been suggesting some level of mixing
Thursday but am concerned those models may be getting rid of cloud
cover too early and indicating mixing that is too strong. Thus, not
sure if soundings that indicate 38-39 kt winds at the top of this
mixed layer will be fully realized. Regardless, it will still be
breezy on Thursday. On the back side of this boundary, progged
dewpoints will remain low in far northwest Missouri, which will
result in lower relative humidity values. With gusty winds, we may
see an elevated fire weather concern Thursday in far northwest
Missouri. As for temperatures Thursday, currently expecting mid 60s
across much of the area as cloud cover keeps us cool along with the
push of CAA. Inner-quartile spread amongst NBM members if fairly
narrow for most forecast points, thus comfortable keeping
temperatures in the mid 60s for the forecast.

Friday, the H5 trough and associated surface cyclone exit the region
and strong thermal ridge pushes across the central CONUS. Low-level
flow shifts southwesterly across the area as the ridge axis
approaches the forecast area, and starts a very robust WAA regime.
Strong AVA will promote subsidence Friday which will quickly work to
dissipate any lingering cloud clover we see on the backside of the
previous system. This will lead to plenty of insolation and should
allow for robust mixing heading into the rest of the weekend.
Ensembles continue to provide a strong signal for anomalously warm
temperatures, looking at the mid 80s across much of the area. For
Saturday and Sunday, inner-quartile spread amongst NBM members and
other ensemble suites is rather narrow with values in the mid to
upper 80s, and the 10th to 90th percentile spread is only about 6 to
7 degrees. Thus, indicating fairly high confidence in well above
normal temperatures for early to mid April. Primarily southwest flow
on Saturday and Sunday will keep moisture return limited, and there
really will not be much in the way of forcing based on the mid-level
synoptic pattern depicted in deterministic model guidance. Ensemble
probabilities for precipitation through the weekend in this strong
WAA regime is less than 15 percent across the forecast area. Thermal
ridge axis passes through the area by early Sunday morning, and a
strong trough over the western CONUS will work to de-amplify the
ridge resulting in brisk zonal flow heading into early Monday. For
the start of the next work week, mid-level flow eventually turns
more southwesterly across the central CONUS. This pattern typically
will find a way to bring precipitation to the area, just depending
on when the Gulf moisture opens back up to the area. Deterministic
GFS and ECMWF still differ on the timing of when the main vorticity
max with the troughing finally ejects eastward, thus leading to
timing discrepancies in precipitation between Monday and Wednesday
of next week. Current ensemble probabilities seem to favor Tuesday
morning for best chance for accumulating precipitation. At this
time, will refrain from assessing any mesoscale details and its
implications for stronger thunderstorm activity.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1225 AM CDT Wed Apr 10 2024

Clear skies to start the overnight hours but a VFR stratus deck
will slowly filter and should be overcast by the middle of the
morning for most of the TAF sites. Most of the ceilings should
be at least 10,000ft which will maintain VFR conditions. Winds
generally around 10 kts during the afternoon.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.

&&

$$

DISCUSSION...Krull
AVIATION...Krull